The type of items in the stream
The string to insert between items
A sink that joins all items into a single string
Behaves like Array.prototype.join(), converting each item to a string and joining them
with the specified separator. Items are converted using their default string representation.
null values are converted to empty strings.
Unlike Array.prototype.join(), undefined values are automatically filtered out
by the stream pipeline before reaching this sink, so they will not appear in the output.
Creates a sink joining all items into a string using a separator.